Historical Import of Physical Activity
Greco-Roman, Chinese, African, and Pre-colonial American literature document the historical importance of physical activity to health and well-being. Paleontologists have established that early humans during the main phases of evolution very likely incorporated regular vigorous physical activity into their daily lives, not only for subsistence and survival but as an integral component of social, religious, and cultural expression. Hippocrates and Galen observed that lack of physical exercise was detrimental to health. So, too, they thought, was overexertion.
Ramazzini in the 1700s, attributed poor health to sedentary occupations when he compared occupational hazards in the sedentary lifestyle of tailors and cobblers to those in more active ‘fleet-footed runners.’ The industrial revolution in England in the 1900s perpetuated health problems of inactive occupations, expressed as greater mortality among sedentary than physically active workers. A 1922 observation of men in Minnesota found those with higher levels of occupational activity had lower death rates.
The modern period of study of physical activity, CVD risk and mortality, may be said to have begun in the late 1940s with Jeremy Morris and colleagues at the UK MRC Social Medicine Unit. They found that highly active conductors on London’s double-decker omnibuses had lower rates and were less likely to die of a heart attack than bus drivers who spent most of their day sitting while driving.
The bias inherent in occupational comparisons soon became evident, however, when it was found that conductors and drivers were much different as young men when they entered these occupations. For example, the drivers already had larger waist sizes in their initial uniform issues. There also was a trend to occupational changes with age, illness, and disability, selecting CHD cases into less active occupations. Morris et al. later reported that postmen who delivered mail by foot had lower rates of CHD than sedentary postal co-workers and supervisors and experienced a gradient of greater CHD rates with decreasing occupational activity. Paffenbarger soon after demonstrated similar findings, and selection bias, among California longshoremen occupations.
The relative power of CVD prediction by questionnaire data on habitual physical activity versus quantitative work capacity or physical ‘fitness’ has preoccupied researchers in recent years. Fitness (defined as work capacity or heart rate at a given workload, or as maximal oxygen intake) is a superior predictor, presumably due to fitness itself and to the greater precision of fitness measurements compared to occupational and leisure time activity questionnaires.
These and other historical studies, led to public health recommendations that have evolved from vigorous activity aimed at cardio respiratory fitness to, at present, more moderate levels of activity for achieving numerous health benefits. (Henry Blackburn)
Berlin, J.A. and Colditz, G.A. 1990. A meta-analysis of physical activity and the prevention of coronary heart disease. American Journal of Epidemiology 132: 612-628.
Powell, K.E., Thompson, P.A., Casperson C.J., and Kenrick, J.S, 1987. Physical activity and incidence of coronary heart disease. Annual Review of Public Health 253.
Leon, A.S. ed. 1997, Physical Activity and Cardiovascular Health: A National Consensus Champaign, IL: Human Kinetics.